Bump error_prone_core from 2.18.0 to 2.20.0

Bumps [error_prone_core](https://github.com/google/error-prone) from 2.18.0 to 2.20.0.
- [Release notes](https://github.com/google/error-prone/releases)
- [Commits](google/error-prone@v2.18.0...v2.20.0)

---
updated-dependencies:
- dependency-name: com.google.errorprone:error_prone_core
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

pom.xml

@@ -24,7 +24,7 @@
     <checkstyle.failsOnError>true</checkstyle.failsOnError>
     <checkstyle.version>10.10.0</checkstyle.version>
     <docker.image>${project.artifactId}</docker.image>
-    <error-prone.version>2.18.0</error-prone.version>
+    <error-prone.version>2.20.0</error-prone.version>
     <extra-enforcer-rules.version>1.6.2</extra-enforcer-rules.version>
     <flatten-maven-plugin.version>1.5.0</flatten-maven-plugin.version>
     <fmt-maven-plugin.version>2.13</fmt-maven-plugin.version>